Most people assume that a sleek, expensive air purifier running in the corner is the gold standard for clean indoor air. That assumption is worth a second look. Long before HEPA filters became a household staple, NASA scientists were already asking a simpler, more elegant question: could ordinary houseplants do the same job?
With people spending more than 90 percent of their time indoors, indoor air pollutants can reach levels two to five times higher than outdoor pollutants, as noted by the Environmental Protection Agency. The air inside super-insulated modern homes and offices can be unhealthy due to volatile organic compounds (VOCs), which cause medical problems. Indoor pollutants include particulates such as dust, mold spores, and pollen, as well as gases released from paints, fabrics, wallpaper, carpeting, and plastics. These are not abstract concerns. They are the air you breathe every day.
The study with the official title “Interior Landscape Plants for Indoor Air Pollution Abatement” was conducted in 1989 by Dr. B.C. Wolverton. Plants were placed in sealed plexiglass chambers, and the air was contaminated with volatile organic compounds such as formaldehyde, benzene, and trichloroethylene. After 24 hours, researchers measured how much of the pollutants had been absorbed by the plants. The results opened a door that science has been walking through ever since.
Why the NASA Clean Air Study Still Matters in 2026
The group of plants chosen for the study was determined by joint agreement between NASA and the Associated Landscape Contractors of America. The chemicals chosen for study were benzene, trichloroethylene, and formaldehyde. The results showed that plants can play a major role in removal of organic chemicals from indoor air.
Perhaps the most important finding, and one that surprised the researchers, was just how, and what part of, the plant was doing the bulk of the filtering: the roots and soil. As part of the experiment, researchers removed all the leaves and learned that the air-purifying effect was only a tiny bit less than before.
Through his research, Wolverton found the air-cleaning capacity of houseplants can be improved exponentially by increasing air circulation to the roots of the plants, where symbiotic microorganisms help make the substances culled from air bioavailable to the plant. This root-and-microbe partnership is what makes these plants genuinely special, not just decorative.
1. Peace Lily (Spathiphyllum ‘Mauna Loa’)
NASA’s top pick, the peace lily removes ammonia, benzene, and formaldehyde, and it even signals when it needs water by drooping slightly. It thrives in low light and looks great doing it.
According to the study, peace lilies removed 23 percent of trichloroethylene from the air in 24 hours, more than any other houseplant tested, a finding which supports their massive popularity. The Clean Air Study also showed that in one day, peace lilies can remove up to a quarter of some airborne toxins. In the benzene test, these plants really stood out, absorbing an impressive 79.5 percent of this toxin.
One honest caveat worth noting: many houseplants are toxic to pets if ingested, and peace lilies are definitely in that category. Keep them out of reach if you share your home with animals or small children.
2. Snake Plant (Sansevieria trifasciata ‘Laurentii’)
The Snake Plant, otherwise known as Mother-in-Law’s Tongue, is unique for its nighttime oxygen production and its ability to purify air through the removal of benzene, formaldehyde, trichloroethylene, xylene, and toluene.
NASA flagged it for absorbing formaldehyde, benzene, xylene, and nitrogen oxides, and it does this even through the night, releasing oxygen while most plants pause. It prefers bright indirect light but tolerates low-light corners well.
Snake plants should be kept near a window, but they only need watering every two to eight weeks. Be careful not to overwater; snake plants don’t take well to too much hydration and can rot easily. For beginners, this is probably the single most forgiving plant on this entire list.
3. Spider Plant (Chlorophytum comosum)
Spider plants are powerful air purifiers that are able to remove formaldehyde, a gas emitted by cigarette smoke, dry cleaning, synthetic carpeting, and fingernail polish, among other sources. Spider plants also remove carbon monoxide, which can be found in rooms with fireplaces or stoves.
Spider plants are non-toxic to humans, dogs, and cats, making them a great choice to clean the air in children’s rooms. They are great for purifying the air from xylene and can even help reduce carbon monoxide, a very dangerous gas.
For those who are houseplant beginners, the resilient spider plant is a perfect choice. It grows fast, adapts to almost any light condition, and produces small offshoots that you can propagate into new plants. Few houseplants offer this much value for this little effort.
4. English Ivy (Hedera helix)
English ivy is the best mold fighter on NASA’s list, shown to eliminate up to 78 percent of airborne mold in just 12 hours. It is ideal for bathrooms and basements where moisture builds up.
The bacteria and mold are reduced because of a phytochemical substance plants secrete into the air. According to a study presented to the American College of Allergy, Asthma and Immunology, English ivy is particularly effective at purifying mold in the environment.
In rooms that held plants, researchers found 50 to 60 percent fewer bacteria and spores of mold than in rooms without plant life. Their findings suggest that plants with large leaves are the most effective, as they have more surface area to contribute to the process of transpiration. English ivy, with its dense trailing foliage, fits that description well.
5. Golden Pothos (Epipremnum aureum)
Pothos is exceptionally adaptable in low-light spaces and has shown capacity for formaldehyde and benzene absorption. It trails beautifully, grows fast, and needs minimal attention beyond occasional watering.
Featured by NASA, the Money Plant (Pothos) is renowned for its ability to remove chemicals and other pollutants from the air, specifically benzene, formaldehyde, xylene, and toluene. It’s the kind of plant that thrives on mild neglect, which makes it a realistic option even for people with genuinely hectic schedules.
Popular plants like pothos, spider plants, and snake plants are especially known for their air purification abilities, thriving even in low light and requiring minimal care. Place one on a high shelf, let it trail downward, and it handles its own air-cleaning business quietly in the background.
6. Bamboo Palm (Chamaedorea seifrizii)
The bamboo palm is one of the higher-rated plants across multiple studies, filtering several VOCs while naturally adding humidity. It prefers indirect light and consistently moist but well-drained soil.
Plants also help improve indoor air quality by humidifying the air, because plants release water vapor as part of photosynthesis and respiration. The bamboo palm takes this humidity contribution further than most, making it a smart addition to dry rooms or apartments with central heating.
Plants can increase humidity in a dry environment, which can be beneficial for respiratory health. They require no electricity and are environmentally friendly. After the initial purchase, plants have minimal ongoing costs. Compared to running a humidifier alongside an air purifier, a bamboo palm pulls double duty for next to nothing.
7. Dracaena (Dracaena marginata / Dracaena fragrans)
Low levels of chemicals such as carbon monoxide and formaldehyde can be removed from indoor environments by plant leaves alone, while higher concentrations of numerous toxic chemicals can be removed by filtering indoor air through the plant roots surrounded by activated carbon. Dracaena varieties are among the most consistent performers in this regard.
The Dragon Tree (Dracaena marginata) is a slow-growing, tree-like plant that can reach over two meters, so it’s best suited to rooms with high ceilings. Water your dragon tree whenever the topsoil is dry, which is usually about once per week.
Beyond carbon dioxide, plants can purify the air from harmful pollutants such as VOCs, carbonyl, particulate matter, nitrates, sulfates, and ammonia. Plants absorb these airborne chemicals through their foliage, break them down in their root systems, and turn them into sugars, amino acids, and other useful building blocks of life. Dracaena’s tall structure and broad leaf surface make it particularly effective at this whole-plant filtration process.
What the Research Actually Says: Real Limits and Real Benefits
A 2019 study by Cummings and Waring in the Journal of Exposure Science and Environmental Epidemiology found that natural air exchange in average rooms exceeds what plants can filter. Researchers at Drexel University echoed this, noting the gap between controlled lab results and real-world conditions.
The honest truth is you’d need hundreds of plants to match a HEPA purifier. But two to three well-placed plants per room still provide a meaningful, passive boost, especially for gases that filters don’t catch.
A 2008 study in India showed that workers in plant-filled office buildings had 24 percent fewer headaches, 52 percent less eye irritation, 34 percent fewer respiratory conditions, and a 12 percent higher lung capacity than workers in plantless environments. Those numbers suggest something real is happening, even if plants are not a direct replacement for mechanical filtration.
How Roots and Soil Microbes Do the Heavy Lifting
In the NASA study, the leaves, roots, soil, and associated microorganisms of plants were all evaluated as a possible means of reducing indoor air pollutants. Plant roots and their associated microorganisms destroy pathogenic viruses, bacteria, and organic chemicals, eventually converting all of these air pollutants into new plant tissue.
As Wolverton proved in his research, the plant and the microorganisms that thrive in the soil around its roots extract organic compounds from the air and turn them into nutrients for the plants. This is the part of the story that rarely makes it into lifestyle articles about houseplants.
Other discoveries include that the more air that is allowed to circulate through the roots of the plants, the more effective they are at cleaning polluted air, and that plants play a psychological role in welfare in that people recover from illness faster in the presence of plants. That second point is easy to overlook, but it matters just as much as the chemistry.
How Many Plants Do You Actually Need?
NASA recommends one to two medium plants per 100 square feet for meaningful VOC reduction. Larger rooms will require more greenery for noticeable results.
For maximum benefit, multiple species of houseplants would likely be needed on a site to remove the relevant toxicants in a particular space, given that houseplants vary in the types of chemicals they are able to remove from the environment and the efficiency with which they do their work.
For optimal indoor air quality, a combined approach using both plants and air purifiers can be highly effective. Plants naturally improve air quality, add humidity, and enhance the aesthetic appeal of the space, while air purifiers quickly and efficiently remove a wide range of pollutants including particulates, VOCs, and allergens. The two approaches are genuinely complementary, not competing.
Beyond Air Quality: The Wider Case for Indoor Plants
Plants play a psychological role in welfare, and people recover from illness faster in the presence of plants. Plants also enhance the aesthetic appeal of a space and can reduce stress and improve mood. These are not trivial side effects.
A study in 2012 supported the NASA study, showing that indoor plants improve air quality in schools and make indoor spaces healthier. The consistency of this finding across different settings, from offices to schools to homes, suggests that the benefit is genuine even if the scale is modest.
NASA research scientists have announced that the common indoor plant may provide a natural way of helping combat sick building syndrome. NASA research found that living plants are so efficient at absorbing contaminants in the air that some will be launched into space as part of the biological life support system aboard future orbital stations. If the standard is good enough for space, it’s probably good enough for your living room.
Conclusion: A Green Layer Worth Adding
None of these seven plants will replace your air filter entirely. The science is clear enough on that. What they will do is quietly, continuously chip away at the chemical load in your home air, add humidity, reduce stress, and contribute something that no machine ever has: a sense of life in the room.
Air filtering plants absorb gases through their leaves and improve indoor air quality over time. They work best alongside mechanical filtration like MERV 13 filters or HEPA purifiers. Think of them as the long game, a passive, low-cost layer of protection that runs without electricity and never needs a filter change.
The most durable lesson from NASA’s decades of plant research may not be about chemistry at all. Plants not only take in carbon dioxide and return oxygen, but they are exceptionally good at capturing harmful toxins from the air. NASA research has delved into how plants do this, and how to potentially use plants to provide clean air on long-duration space missions. If living green helps sustain humans in orbit, keeping a few on your windowsill seems like a very reasonable place to start.
